I've been hearing rumors that the Pyro is in fact the Scout's mother- And I somewhat believe it because Valve hasn't intruduced a character in TF2 that you cannot see in-game, therefore, the only plausible answer would be that the Scout's mother is the Pyro, But hey, don't yell at me because I think it's true, because I know someone will call me a loving handicap.
EDIT: The announcer is, I believe, a supercomputer.